Vulcanization of rubber



' Patented June 16,1930

UNITED STATES.

DONALD E. POWERS, OF PEN NS GROVE,

PATENT OFFICE NEW JERSEY, ASSIGNOR TO E. I. PONT DE WARE N Drawing.

\ This invention relates to an improvement inthe vulcanization of rubberand more partieu'larly to the use of a new compound as an accelerator ofvulcanization to be more specifically referred to hereinafter.

I have discovered that benzo thiazole monosulfides constitute excellentaccelerators for the vulcanization of rubber and provide a superiorrubber product. I have also found 10 a convenient and suitable processfor the formation of this type of accelerator compound. The applicationof these accelerators or agents in the vulcanization of rubber may becarried out in 'a manner already generally known in the art. That is tosay, the formulas, mode of mixing, etc., may be varied very widely inmaking use of this new class of accelerators. t

I, therefore, give merely by way of a suit- 'able embodiment of theinvention the following composition of stock:

' .Parts Amber crepe 50 Smoked sheets 50 Zinc oxide u 3 Sulphur a 3.5Thiazyl monosulfide 1 The usual manipulative procedure adopted in thevulcanization of rubber may, of course,

be applied in this case also and the temperatures offvulcanization usedwill, of course, be

controlled in a suitable manner with the un;

' derstanding that a lower temperature of vulcanization may be used if alonger time of 5 curing and a larger percentage of the accelerator isemployed, and that when using higher temperatures a shorter time of cureor less accelerator may be used.

I have found that various benzo thiazole 40 monosulfides may be thusemployed and for purposes of illustration I include the follow- 'ingtable to show the general effects of certam accelerators, although it isto be understood that these values are not limited, and

may, of course, vary to some extent, according V'ULCANIZA'IION OI RUBBERApplication filed August 31, 1926. Serial No- 132,895.

to the manner of curing, the quantities of ace celerators and generalconditions of compound ng and vulcanization.

Cure g t s r a Elongabreak g Pressure (lbs/sq minutes (pounds) Benzothiazyl monosulphide- 20 40 2 420 800 3-methu1 benzo thiazyl mono- 20 403 1040 815 sulphlde 30 30 3, 230 810 Naphtho thiazyl monosulphide. 20 403,060 815 I have also discovered a method of preparing the acceleratorsto be used in the carrying out of this invention, and as an example Ipresent a process for the production of benzo thiazole monosulfide asfollows:

Two thousand pounds of sodium mercapto benzo thiazole prepared bydissolving mercapto benzo thiazole in the calculated amount of dilutecaustic soda solution, is made up to a weight of twenty thousand poundsof aqueous solution. This solution is preferably cooled below'10 C. andwhile being agitated, six hundred and fifty pounds of cyanogen chlorideare added using the usual precautions for handling this material andavoid.

ing over-heating. The benzo thiazole monosulphide separates as a yellowcrystalline waterdnsoluble product. It may be readily recrystallizedfrom alcohol, but the product as it separates from the aqueous solutionis of very good purity. The monosulphide is then filtered and dried.-

may also be starting with the substituted benzo thiazole. Of particularimportance is the methyl benzo thiazole monosulfide prepared from3-methyl benzothiazole. Alkyl, hydroXy,v or alkoxy substituted benzothiazole monosulfides may also be pre ared and used to aid thevulcanization of ru ber or to act as accelerators therein, as the casemay be, and these and other Substituted benzo thiazole monosulfidesprepared in a similar manner thiazole mono-sulphide.

modifications in this class of compounds are to be understood as beingcom rise'd i-withm the scope of my inventlon. e 7probable mechanism ofthe reaction for the formation of these compounds is "as-follows:

- a \-s-m+on.nmae

As many apparently widely diflerentem bodiments of this invention may bemade without departing from the spirit thereof, it

is to be understood that I do not limit myself to the foregoing examplesor description, ex-

cept as indicated in the following patent claims.

'I claim: 1 1; The process of treating rubber, which comprisesvulcanizing said rubber in the presence of di benzo thiazolemono-sulphide;

2. The process of treating rubber, which comprises heating the same witha vulcanizing agent in'the presence of a small proportion of a reactionproduct of a mercapto benzo thiazole and a cyanogen halide.

3. The process of vulcanizing rubber comprising heating the same in thepresence'of I a vulcanizingagent and a yellow crystalline product"formed by the reaction of cyanogen chloride and the sodium saltof=mercaptobenzo-thiazole, said product being soluble in alcohol. .andinsoluble in water.

4. The. process of treating rubber which comprises vulcanizing saidrubber in the presence of a member of the group consisting of 'di benzothiazole mono-sulphide, di-3-methyl benzo thiazole mono-sulphide anddinaphtho In testimony whereof I aflix my signature.

DONALD H. POWERS.

